Question

Which of the following has higher dipole moment and why? But-1-ene or But-1-yne​

Answer 1

But-1-yne

But-1-yne will be more electronegative than But-1-ene. This is because the C in but-1-yne is sp hybridised which is more electronegative than the C in but-1-ene which is sp. Greater electronegativity means greater electronegative difference and thus higher dipole moment.$\:$

Answer 2

Since a sp carbon is more electronegative than a sp2 carbon, therefore, the dipole moment of CH3CH2(sp3)-C(sp) bond in 1-butyne is more than that of CH3CH2(sp3)-C(sp2) bond in 1-butene. As a result, the dipole moment of 1-butyne is more than that of 1-butene.